1. Technical Field
The present invention relates to an actuator device including piezoelectric elements displaceably provided on a substrate, to a liquid-jet head and to a liquid-jet apparatus both of which use the actuator device.
2. Related Art
As a piezoelectric element used for an actuator device, there is one constituted by interposing, between an upper electrode and a lower electrode, a piezoelectric layer made of a piezoelectric material exhibiting an electromechanical transduction function. An example of such piezoelectric materials is crystallized piezoelectric ceramic. Such an actuator device is generally called an actuator device of flexure vibration mode, and is used by being mounted on a liquid-jet head or the like. Representative examples of the liquid-jet head include an ink-jet recording head in which a part of each pressure-generating chamber communicating with a nozzle orifice that ejects ink droplets is composed of a vibration plate. This vibration plate is deformed by a piezoelectric element to apply pressure to ink in the pressure-generating chamber, and thereby ink droplets are ejected from a nozzle orifice. On the other hand, in an actuator device mounted on the ink-jet recording head, the piezoelectric elements are formed to be independent of one another, and are provided to the pressure-generating chambers, respectively. For this purpose, first, a uniform piezoelectric material layer is formed all over an entire surface of the vibration plate by a film-formation technique, and then the piezoelectric material layer is cut into shapes corresponding to the respective pressure-generating chambers by a lithography method.
Here, the piezoelectric element is formed by stacking, sequentially, a lower electrode, a piezoelectric layer and an upper electrode. The lower electrode is formed by stacking, sequentially, an adhesive layer, a platinum layer and a diffusion preventing layer on a single-crystal silicon substrate, while the piezoelectric layer is constituted by a crystallized piezoelectric film that is made by baking a piezoelectric precursor film formed of a piezoelectric material (see, for example, WO99/45598, pp. 19-23, FIGS. 12-14.).